1. Field of the Invention
The present invention relates to a semiconductor integrated circuit. More particularly, the present invention relates to a semiconductor integrated circuit suitable for use in a wireless communication baseband (BB)-LSI (Large Scale Integrated circuit) on which a DAC (digital-analog converter) and an ADC (analog-digital converter) having substantially the same accuracy are mounted.
2. Description of the Related Art
At present, in a BB-LSI conforming to a standard “802.11a” for wireless LAN (Local Area Network) communication determined by the Institute of Electrical & Electronics Engineers (which will be referred to as IEEE hereinafter), an LSI tester is used to screen fair-quality DACs and ADCS. That is, the LSI tester is used to generate a test signal for screening conforming items and analyze a response signal with respect to this test signal. Therefore, there is a problem of a cost.
To reduce the cost, it is desirable for the BB-LSI itself to generate a test signal and analyze a response signal. For example, there can be considered a method of supplying an internally generated test signal to a DAC, allowing an output from the DAC to pass through (loop back) an ADC, and analyzing a response signal obtained from this output by using a matched filter. However, in this method (using the matched filter to analyze the response signal), a result of the analysis fluctuates according to the passage delay amount of a loop back signal. There is a therefore a drawback that adjustment is required at the time of configuring a screening environment in order to compensate this fluctuation.
Further, utilizing a built-in FFT (Fast Fourier Transform) included in the BB-LSI to analyze the response signal can be also considered (see, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2004-048383). However, since the FFT is specialized for OFDM (Orthogonal Frequency Division Multiplexing) transmission/reception, its accuracy is insufficient for analysis of the response signal. Furthermore, since it is used for both transmission and reception, complicated control is required, and diverting it for a loop back operation is not easy.